#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
#define INF 0x3f3f3f3f
using namespace std;
ifstream in("ubuntzei.in");
ofstream out("ubuntzei.out");
int n, m, k, i, p, x, y, dist[2005], Min=INF,c;
vector <int> g[2005], cost[2005];
queue <int> Q;
int main()
{
    in>>n>>m;
    in>>k;
    for(i=1;i<=k;i++)
    {
        in>>p;
        Q.push(p);
    }
    for(i=1;i<=n;i++)
    {
        in>>x>>y>>c;
        g[x].push_back(y);
        g[y].push_back(x);
        cost[x].push_back(c);
        cost[y].push_back(c);
    }
    for(i=2;i<=n;i++)
    {
        dist[i]=INF;
    }
    Q.push(1);
    while(!Q.empty())
    {
        x=Q.front();
        for(i=0; i<g[x].size(); ++i)
            if(dist[g[x][i]] > dist[x] + cost[x][i])
            {
                dist[g[x][i]] = dist[x] + cost[x][i];
                Q.push(g[x][i]);
            }
        Q.pop();
    }

    out<<dist[n];
    return 0;
}